Treatment of coal-gas and analogous gases for obtaining tar and ammonia.



W. FBI ID.

TREATMENT OF GOAL GAS; AND ANALOGOUS GASES FOR OBTAINING TAB AND AMMONIA.

APPLIOATION T'ILED SEPT, 27, 1907.

951,778, I Patented Mar. 8, 1910.

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Aft-o mqs.

W. FELD. TREATMENT OF GOAL GAS AND ANALOGOUS GASES FOR OBTAINING TAB AND AMMONIA.

APPLIQATION FILED 811F127, 1907.

Patented Mar. 8, 1910.

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F m, M flttownegs Walther MON IA.

W. FELD. TREATMENT OF GOAL GAS AND ANALOGOUS GASES FOR OBTAINING TAB AND AM APPLICATION FILED SEPT. 27, 1907.

Patented Marl8, 1910.

3. D m P L m m H N k N m a V E m m l v H 3 I. II! n m W T IIMIN Q a E M M. n W m N HE m iw v 'PSVS w s Q Y Q? kw ov m 0 o. S .M m w mm 7h, N m

Attorney UNITED srATEs PATENT on if o 1 WALTHER-FELD, or HfiNNINGEN-ON-THE-RHINE, GERMANY.

I TREATMENT or cont-ens AND DANALOGOUS eases roa'oi ammme TAR an]:

AMMONIA.

Specification of Letters Patent. I Patent ed Mar, 8, 1910."

Application filed September 27, 1907. Serial No. 394,865

To all whom it may concern:

Be it known that I, NVALTHER FELD, a subject of the King of Prussia and the German i y by steam and the products of distillation,-

such as benzole and its homologues, water,

Emperor, residing at Honningen-on-the- Rhine, in the Kingdom of Prussia and German Empire, have invented new and useful Improvements in the Treatment of Coal- Gas and Analogous Gases for the Obtainmentof Extraneous Matters such as Tar Constituents and Ammonia Therefrom, of which the following is aspecification.

- My invention has-for its object to effect the obtainment of extraneous matters (such for example as tar constituents, cyanogen, ammonia, and the like) from coal-gas and analogous gases in a more economical and eflicient manner than hitherto.

Hitherto tar has been separated from coal gases and the like by cooling them to a low temperature, or, as described in the specification of British Letters Patent No. 26,262 A. D. 1905 granted to me, by washing such gases with the separated tar itself and in order to split the tar, produced in either of these ways, into its constituents, it has been distilled in vessels heated by an open fire, or

ammonia, and the various tar oils, were separated from one'another by fractional distillation.- ,As a rule, the oils, obtained by tar distillation according to their various boiling points, are classified as follows Light oils with a boiling point up to about 170 centigrade, creosote oils with a boiling point from about 170 to about-230'centigrade, heavy'tar oils with' a boiling point from about 230 to about 270 centigrade,

anthracene oils with, a boiling point from about 270 to about 320 centigrade.

The matters remaining in the distilling vessel, and consisting of a mixture of car= bon with hydrocarbons of a. boiling point about 320 and above centi rade, are classified as pitch. Vapors 0 such solids and liquids as can be evaporated above, at dif ferent temperatures, different tensions, the tension being higher the nearer such product is heated to its boiling point. According to this tension, any gas being in contact with such matter will'contain, at a certain temperature, a corresponding amount of vapor,

which amount is the higher in proportion to the higher temperature of the gas. A gas in such condition is said to be saturated with the vapor of the given substance. If such saturatedgas of a given temperature B be cooled down to a lower temperature A, so

much of the vapors must condense, or separate from the gas, as corresponds to the difference between the tension 10f such vapors at the former temperature B, and at the lower temperature A. If, on the other hand, a gas in such saturated condition, at a ternperature B, be heated to ahigher temperature C, without being in contact with the 'vaporizable substance, the gas, at the temperature C, will not besaturated with the vapors, and vice versa, such gas being cooled down to under the temperature C,no condensation, or separation, of the vapors can occur until, the gas is cooled below the temperature B. The temperature B is the dew point of the gas with reference to the given substance; thatis to say, as long as the gas is not cooled to under the dew point B, no transformation of the vapors in question into liquid, or solid, form, and therefore no separation, can occur. Coal-gases and similar gases, at the temperature at which they leave the ovens, or retorts', are in this un-.

saturated condition as regards most of the constituents of such gases. The dew points of such gases, for their different constituents, are at .diiferent, gradually decreasing, temperatures according to the amounts thereof present and their boilin point. According to one of the featuresot my invention I utilize this property so that the heat of the gases themselves is employed to efi'ect the required separation of the desired constituents therefrom by a system of frac-i tional coolings, or of fractional coolings combined with successive washings.

I havefound that, commonly, the dewpoints of ordinarycoal-gas formost of its tar constituents of high boiling points lie below. 200 centigrade, that is to say, so-

long as such gases are not cooled below 200 Centigrade no suchconstituents will be condensed, and of course, if the dew point of such gas for water'be 75 centigrade, no water will be condensed until the gas is cooled below that temperature. As a rule,

the pipes, or passages, which lead from the ovens, or retorts, to the condensing plant are at present arranged in such a way that the portion of the gases which comes into contact with the inner walls of such pipes, or passages, is locally cooled, not only below the dew point of the said tar constitucuts, but even below the dew point of wa ter, and consequently, gasconstituents are condensed on the inner walls of such pipes, or passages, while the remainder of the gases passing through the middle of such pipes,

(soot) in the gases andtherefore of the formation of tar, and clogging of the pipes, or passages, with carbon. According to a further feature of my invention I may precede the treatment by fractional coolings, or fractional coolings and successive washings, by preventing, as far as possible, the formation of tar itself, (that is to say, a mixture of hydrocarbon with free carbon, or soot), in order to obtain, free of carbon, tar constituents of higher boiling points, before the gasesenter the first cooler, or washer, but this invention is capable of use also incases where constituents of lower boiling points only are required to be separated in which case this prevention of the formation of tar itself need not be, employed.

In cases where the deposit of carbonand consequent formation of tar in the gases as they come from the retorts, or-ovens, is to be prevented, I can elfect this by maintaining the heat of the said gases above, or prevent ing their cooling to the dew pointof the sald gases for their constituents of the highest boiling point. This may be done in various ways for example, by covering the pipes, or passages, which lead from the ovens, or retorts, to the first vessel, or washer, (used in the process of separation by fractional coolin s, or fractional coolings and successive was ings) with a non-conductor, or bad conductor, of heat, or by applying heat to the exterior of the said pipes, or passages, or by gradually increasing the sectional area of the pipes,'or passages, ac-

, cording to the number of ovens, or retorts,

which are in communication therewith or by introducing suitable diluting gases, steam, or other vapor, (superheated, or not,)

into the retorts, or ovens, or the passage therefrom, with the object of increasing the volume of the gases containing the tar constituents; or by two, or more, such means used in combination. The gases after passing from the said pipes, or passages, can be' conducted, for treatment according to my invention, into any suitable vessels adapted to effect the fractional coolings, or fractional coolings and successive washings at successively lower temperatures, so that various gas constituents are separated from each other by employing the temperature of the gases themselves without the necessity for the hitherto commonly practiced plan of employing extraneous heat for distilling the constituents from each other, after previous cooling.

The treatment by fractional coolings, or fractional coolings and successive washings,

can be applied to the recovery of any, or all,- of the constituents to be recovered from the gases, for instance it can be applied (in cases where the formation of tar has been prevented as aforesaid) in two, or more, vessels, for the recovery of tar constituents of the higher boiling points at successively lower temperatures, in such awaythat the temperature in the second, or last, vessel is.

higher than the dew point of the gases for water, or (without the revious prevention of the formation of tar; the water and tar constituents of lower boiling pointcan be separated from the gases in two, or more, vessels, by successive coolings, or coolings and washings; and generally the treatment can be' applied in a number of" successive stages to obtainall, or any desired number,

of the constituents, or extraneous matters,

from the gases.

WVhen, according to this invention, is-

required to separate, or absorb, a constituent, or constituents, in a pure, or practically pure, condition; the volume of the gases may be increased in order to raise the gases above the dew point of any undesired onstituent, or constituents, so that the desire constituent, or constituents, is or are,de osited, or

absorbed, free, or practically tree, from any undesired constituent. This increase of volume can be effected in various ways, such as according to the methods described, in the specification of my British applications for Letters Patents Nos. 27,567, 27,568 and 28,390 A. D. 1907, for example by adding gases, or vapors, (heated or not) which contain none, or less, of the undesired constituent, or constituents, or by slightly heating the crude gases.

In, the process according to the present invention the cooling of the gases at one stage may be effected by washing them with a product, or products, of a further stage, or-

further stages, the said product, or products,

being, or containing, a hquid'with which the gases, at the given temperature, are not saturated, in order to lower the temperature of the gases by evaporation of the said liquid, and generally by'cooling the gases at one stage by washing them with a liquid, or liquids, derived from a further stage, or

further stages, of the rocess. These liquids may be derived from t e gases themselves, or from other source and may be used heated, or not, according to their nature and to the special conditions.

I will now describe how my invention can be carried out, presuming, for example-that the process is to include the preliminary prevention of the formation of tar.

In the accompanying drawings in which are illustrated suitable means for conveying the gas from the ovens to the recovering a paratus, Figure 1 is a sectional elevation o a ry conveyer main; Fig. 2 is a broken side elevation thereof at right angles to Fig. 1; Fig. 3 is a'sectional elevation of a hydraulic conveyer main; and Fig. 4 is a side elevation atright angles thereto. Fig. 5 is a diagrammatic elevation partly in section, of a suitable apparatus for carrying out my process. 1 To prevent the ascension pipes becoming clogged with carbon, they at present have a diameter which is, in mostcases, too wide for the amount of gases which passes through them. If they have a smaller diameter, the ascending gases pass through them at a higher speed and consequently are less expose to the cooling influence of the walls of the pipes, or passages. For the same reason, the pipes, or passages, which lead the gases from the ascension pipes to the cooling and washing apparatus should have a gradual increase in their sectional area, which increase is in accordance with the number of oltl ens, or retorts, in communication with t em.

Figs. 1 and 2' of the accompanying drawing show, in transverse section and side elevation res ectively the two endportions of a so-called dry main. The pipe 1' leading from the main to the first apparatus is fixed at the end a of the main. The sectional area of the main, which may be supposed to be in communication with sixty ovens, is gradually increased from the part where the first ascension pipe .9 enters up to the part where the last ascension pipe 8 enters. The communication between the main and the retorts, or ovens, may be shut off by the valves 0.

Figs. '3;-and 4 show in transverse section and side elevation respectively, a hydraulic main with the ends of the ascension. pipes dipping into theliqu'id in the main. The pipe rleading from the main to the first apparatus is fixed in the middle of the main, and therefore the sectional area of the main is increased gradually from both ends to the middle. If these arrangements be not sufficient to maintain the heat they may be supplemented or substituted by any suitable expedients for this purpose. The gases'coining from the retorts and containing the tar products and water in the form of vapor,

(Fig. 5). This apparatus in the form shown, to which however, -I do not confine myself, comprises .gas washers A, B, C and E, preferably of the vertical type described in my Patent 829,261.

Dis a cooling tower for the gases, while F is a cooler for cooling water or oils.

G, H, K, L and M are tanks and b, c, d liquid pumps.

The gas enters at a the first washer A at a temperature from'l80 C'. to 200 0., or above. The dew point of the ases for those tar constituents havinga bolling point of 300 C. or higher may be say 160 C. The gas must therefore be cooled to this temperature, and while this may be accomplished in any desired 'way, I prefer to wash the gases with the liquor condensed at a lower temperature (as will be hereinafter explained) in the second washer B. This liquor is forced to the washer A from the tank L by the pump 5. So muchof the tar constituents with a boiling point above 300 C. will be separated as are contained in the gases above the quantity which corresponds to the point of saturation and will run off through the pipe m, to the tank M, being in a liquid state, and will become solid at a temperature of approximately C. according to the amount of free carbon and such hydrocarbons as are solid at ordinary temperatures. Such tar oils having boiling points under 300 C. as are contained in the washing liquor drawn from the tank L, are evaporated (thereby cooling the gas in the washer A) and pass with the cooled gas to the seco washer B.

The gas coming from the first washer is practically free from free carbon and tar and contains practically all the gas conpoint for water being 75 centigrade) will e separated. In order to effect the separation, the gas is cooled from 160 centlgrade to, say, 80 centigrade in a similar manner vlz., by washing the gases with the products of condensation from the third washer C.

. The lowest boiling point of the product running off from the washer may be 180 cen' tigrade. Besides products with a boiling point from 180 Centigrade to 300 centigrade, this product will contain so much of the products with a boiling point above 300 centigrade as corresponds with the falling ofthe tension of the gas for' the products with a higher boiling point than 300 centigrade. It is for the purpose of getting these products of a boiling point above 300 centigrade, as much as possible separated from those with a lower boiling point, that I use as much of the liquor coming from the second washer as the washing liquor for the first washer as is possible withoutlowering the temperature in the first washer to under 160 centigrade. If this liquor enters the first washer, there will be a strong evaporation of those constituents with a lower boiling point than 300 centigrade, with which the gases are not saturated at 200 centigrade, whereas the constituents with a boiling point of 300 centigrade and above, with which the gases are saturated at 160 Centigrade, cannot be evaporated. This has proved to be the best means to cool the gases,-a means which .at the same time allows a further splitting of the gasconstituents than would'be possible by simply have been drawn from this source, for the successful operation of my process.

The cooling in the third washer C, to say 60 C. is effected by tar products from the cooling tower D, in which tower D the gases are cooled, by water, to under the dew-point of steam in the gas, say down to 20 or 30 centigrade. The bulk of the steam in the gases and part of the light oils are conby the pipe at to, and is washed in the washer densed and the liquids are both run off from the tower bythepipe and are stored in the,

tank Gr, inwhich the-light oils separate from the water owing to their different specific gravity. The oil bein water runs by the over ow h'into the tank H, whence part of it'is pumped by the pump id up to the washer C. The water flows by the siphon f into the water tank P. This water contains ammonia which can be distilled off. i

The gas coming from the tower D saturated with light oils, and in order to extract the said oils from the gas it passes .15 with heavy tar oils pumped from the tank L, through the pipe f and cooled in the cooler F, before they enter the washer E. The heavy tar oils act in the washer E as a solvent, for light tar oils and run off from the washer through the pipe is into tank K, from which they are agam pumped up to the washer B, Here the light oilsare evaporated and the heavy tar oils, together with those condensed in the washerB run into the tank L by the plpe Z. The light tan-oils, evaporated in thewasher B will be again temperature ofthe ases themselves.

lighter than the.

eta-27a condensed in the tower D. By the constant circulation of the different tar products,

their quantity will be increased by those cbndensed from the gases passing through the washers and the surplus is run off-from the respective tanks and can be sold, or used for any desired purpose;

It will be readily understood that the number ofwashers may be varied to get any desired gradation of tar constituents, and that the temperatures of the washers may be varied as desired. Thus, instead of starting with a temperature of 200 centigrade,.

or above, the first washing, or state of the process, may be effected at a temperature below the dew point of water if only the lower boiling gas constituents are required to be separated from the tarry matters. If i the gases contain ammonia, the water condensed will absorb part of this. In this case the method described in my aforesaid former specification of British Letters Patent No: 26262/05 may be used to reconduct the ammonia intothe gas to be separated afterward. vAlso an other convenient method for the extraction of ammonia, cyanogen, and other extraneous matter, may be used. If such extraction be effected in such a way that the gas is at the same time cooled, the extracted substance will be vcontaminated with tar oils, but contamination of the desired constituent by an undesired constituent can be prevented as aforesaid if the volume of the gas be increased above the dew point of the undesired constituent so that it is not separated. This can be effected by using a washing material (in which ammonia, or any other extraneous substance, may be absorbed) with a higher temperature than the If for example the absorblng agent be dissolved in water, the hot water -(even though it be but to a small amount) will raise the heat of the gases and thus the .now unsaturated gases, will evaporate water and the volume of the gases will thus be raised above the dew point of the undesired constituent;

If the'special conditions would not allow of preventing the formation of tar, I may first separate the tar and then separate those tar oils and other gas constituents from the gases, which, according to the temperature atthev-firsmstage', are not present in such 'qliliantities that the gases are saturated with I claim as my invention:

the various constituents of hot coal or analo-- gous gas, the recovery from said gas of the vaporized tar constituents separately from each other by'leading said gas from the oven or retort in which it' is produced to a cooling apparatus at a temperature above that of condensation of'the tar constituenthaving the highest dew point, cooling said gas in successive steps to the successive dew points of the various desired tar constituents of the gas and recovering said tar constituents separately as they successively condense, substantially as described.

2. In the process of extracting separately thevarious constituents of hot coal or analogous gas, the recovery from said gas of the vaporized tar constituents separately from each other by leading said gas from the oven or retort in which it is produced to a cooling apparatus at a' temperature above that of condensati n of the tar constituent having the highes dew point, cooling said gas in successive steps tothe successive dew pointsof the various desired tar constituents of the gas, washing said gas at said successive steps and recovering said tar constltuents separately as they success1vely con- I dense, substantially as described. 3. In the process of extracting separately the various constituents of hot coal or analogous gas,-the recovery from said gas of the vaporlzed tar constituents separately from each other by leading said gas from the oven or retort in which it is produced to a cooling apparatus at a temperature above that of condensation of the tar constituent having the highest dew point, leading said gas through a plurality of chambers therein, cooling said gas in said successive chambers to the successive .dew points of the various tar constituents of the gas and recovering the latter separately as they successively condense, substantially as described.

4. In the process of extracting separately the various constituents of hot coal or analogous gas, the'recovery from said gas of the vaporized tar'constituents separately from each other by leading said gas from the oven or retort in which "it is produced to a cooling apparatus at a temperature above that of condensation of the tar constituent having the highest dewpoint, leading said gas through a plurality of washing chambers therein, cooling and washing said gas in said successive chambers at the successive dew'points of the various tarconstituents of the gas and recovering the latter se arately as they successively condense, substantially as described.- I

5. The process of extracting separately the various vaporized constituents of hot coal or analogous gas, which consists in leading said gas from the oven or retort in which it is produced to a cooling apparatus at a temperature above the dew'point of the desired constituents, cooling said gas. in successive steps to thesuccessive dew points of the various constituents, increasing the .vol ume of the gas under treatment at any desired step in the process to raise the gases above the dew point of an undesired constituent and recovering the desired constituents as they successively condense.

6. The process of extracting separately the various vaporized constituents of hot coal or analogous gas, which consists in leading said gas from the oven or retort in which it is produced to a cooling apparatus at a temperature above the dew point of the desired constituents, cooling said gas in successive steps to the successive dew points of the various constituents, increasing the volume of the gas under treatment at any desired-step in the process by adding a quantity of a gas capable of absorbing an undesired constituent so as to lower the dew point of the gas under treatment with respect to the undesired constituent, and recovering the desired constituents as they successively condense.

7. The process of extracting separately the various vaporized constituents of hot coalor analogous gas, which consists in leading said gas from the oven or retort in which it is produced'to a cooling apparatus at a. temperature above the dew po1nt of the desired c nstituents, cooling said gas in successivesteps to the successive dew points of the various constituents, increasing "the vol- .ume of the gas under treatment at any desired step in the process by adding a quandesired constituent so as to lower the dew point of "the gas under treatment with respect to the undesired constituent, and recovering the desired constituents as they sn'ccessively' condense.

8. The process of extracting separately the various vaporized constituents of hot coal or analogous gas, which consists in leading said gas trom the oven or retort in which it is produced to a cooling apparatus at a temperature above the dew point of the desired constituents, leading said gas through a plurality of chambers therein, cooling said gas in successive steps to the dew pomtsof the various desiredconstituents while maintainin the gas above its dew point for water inv said successive steps, in successive chambers therein and recovering the various constitutents of the gas asthey successlvely condense. 4

9. The process of extracting separately the various vaporized constituents of hot coal or analo ous gas, WhlCh cons sts 1n leading said gas trom the oven or retort in which it is produced to a cooling apparatus at a temperature above the dew point of the desired constituents, leading said gas through a pluralityfof washing chambers therem, cooling said gas in successive steps to the dew points 0 the various desired constituents while maintaining the gas" above Its dew point for water in said successive steps therein, and recovering the various constituents as they successively condense.

10. The process of extracting separately the various vaporized constituents of hot coal .or analogous gas, which consists inleadQ ing said gas iromthe ovenor retort in which itis. produced to a cooling apparatus at a temperature above the dew point of the desired constituents, cooling the same in successive steps to the successive dew points of the various constituents by washin the-same at one stage witha liquid of anot er'stage,

' the said liquid containing matter with which coal or analogous gas, which consists in. lead- 1 ing said gas trom the oven or retort in which it is produced to a cooling apparatus at. a

temperature above the dew' oint of the desired constituents, cooling t e same in success'iv'e steps to the successive dew points of the various. constituents by washing the ,recO'veri'ng the various constituents of thegas as they. successlvely condense.

same at one stage with a liquid of another stage, the said liquid being at a lower temperature than the gas treated therewith, and

12. The \process of extracting separately the various vaporized constituents of hot coal or analogous gas, wh1ch conslsts in leadingthe gas asit comes from its generator to the treating apparatus at a temperature above the dew point of the gas. for. itsiconstituents of the highest boiling point, cooling-said gas in successive steps to the successive dew points of the various const1tu-.

ents, and recovering the latter as they successively condense.

'13. The process of extracting separately the'various, vaporized constituents of hot coal oranalogous gas, which consistsin leading the gas through a conduit from -its ,gen-.

erator to thejtreating apparatus, treating said conduit to maintain the temperature of the gas above itsdew' point for its constitu it ents of the highest boiling point, cooling said gas in successive steps to-the successive dew points of the-various constituents,- and reeemve covering the latter as they successively condense.

14c. The process of extracting separately" the various. vaporized constituents of hot coal or analogous gas, which consists in leading said gas in. a singlestream of increas-.

ing volume from a plurality of generators .to the treating apparatus at a practically uni-form pressure and speed, cooling said gas in successive steps to the successlve dew polnts of the various constituents and recovering the latter as they successively con-f dense. r Y 15. The" process of extracting separately the various vaporized constituents of hot coal or analogous gas, which consists in lead- .ing said gas from the oven or retort in which it'is produced to a cooling apparatus at a temperature above the dew point of the desired constituents, dilutingsaid gas to increase its vdlume before it reaches the'treating apparatus, cooling said gas in successive steps in the latter to the successive dew points .of the various constituents, and recovering the latter as they successively conv dense.

16. The process of extracting separately the various vaporized constituents of hot coal oranalogous gas, which consistsin leading said gas from the oven or retort in which" itis produced to a cooling apparatus at a temperature above the dew point of the de cessive steps to the successive dew points of "the various constituents, recovering the lat-. teras they successively condense and washing the gas ata'. lowered'temperature with 'a'pro'duct of'a former stage whereby a con- I 'stituent of lower boiling point is dissolved" by a constituent-of hi her boiling point, sub stantially as describe In testimony whereof I have signed my sired constituents, cooling the same in'sucname to this specification in the presence of V two subscribing witnesses. f r

. -WALTHER FELT).

Witnssesi, GILBERT FLETCHER Tyson, WILpIAM GERALD v REYNOLDS. 

